Optical correction layer for a light emitting apparatus

Abstract

An optical correction layer for a light emitting apparatus having gaps in brightness at the light-emitting surface. The optical correction layer includes a plurality of optical correction regions centered over the gaps, and a plurality of optically transparent regions which overlay the remainder of the light-emitting surface. The optical correction regions include appropriately formed grooves which collect and redirect light adjacent the gap. The light is redirected to cover and effectively conceal the gap. The optically transparent regions permit light to travel through, without redirection.

What is claimed is: 
     
       1. An optical correction layer for concealing a gap in brightness at a light-emitting surface of a faceplate of a light-emitting apparatus having light-emitting regions adjacent the gap, the optical correction layer comprising: an optical correction region having a first height and having a width equal to the sum of the width of the gap and the widths of light-emitting regions adjacent the gap so that, when the optical correction region is substantially centered over the gap, the optical correction region opposes the gap and the light-emitting regions adjacent the gap;   means being disposed within the optical correction region for redirecting light so that the light-redirecting means receives and redirects the light emitted from the light-emitting regions to substantially cover and conceal the gap; and   a plurality of optically transparent regions having a second height substantially equal to the first height of the optical correction region, the optical correction region being positioned between the plurality of optically transparent regions so as to form a continuous layer of substantially uniform height, the continuous layer having first and second opposed, planar surfaces, the first planar surface including an outer surface, the second planar surface being designed to be affixed to the light-emitting surface of the light-emitting apparatus so that the optical correction region is substantially centered over the gap in brightness,   whereby the optical correction layer provides substantially uniform brightness over the light-emitting apparatus and substantially conceals the gap in brightness.   
     
     
       2. An optical correction layer as claimed in claim 1 wherein said continuous layer is made of plastic. 
     
     
       3. An optical correction layer as claimed in claim 2 wherein said light-redirecting means includes a light-collecting groove formed in the second planar surface of said plastic, continuous layer and defining a central region, said light-collecting groove having a first concave, reflective surface and a second transparent surface, said first concave, reflective surface and said second transparent surface meeting at a vertex, the light-collecting groove being disposed opposite the light-emitting regions adjacent the gap so that the first reflective surface receives light from the light-emitting regions and reflects the light to travel through the second transparent surface; and further includes a central groove formed in the second planar surface of said continuous layer, the central groove being position in the central region defined by the light-collecting groove, the central groove having a convex, reflective surface forming an apex positioned substantially opposite the center of the gap, the convex, reflective surface being positioned to receive the light reflected by the light-collecting groove and having a predetermined curvature so that the light is reflected and redirected to substantially cover and conceal the gap in brightness.   
     
     
       4. An optical correction layer as claimed in claim 3 wherein the outer surface of said continuous layer includes a light-diffusing surface. 
     
     
       5. An optical correction layer as claimed in claim 3 wherein said first concave, reflective surface includes a thin coating of aluminum and wherein the convex, reflective surface includes a thin coating of aluminum. 
     
     
       6. An optical correction layer as claimed in claim 3 wherein the light-collecting groove includes a circular trough defining a circular central region and encircling said central groove and wherein said central groove includes one continuous surface. 
     
     
       7. An optical correction layer as claimed in claim 3 wherein the light-collecting groove includes a pair of elongated troughs defining a rectangular central region. 
     
     
       8. An optical correction layer as claimed in claim 3 wherein the second planar surface is affixed to the light-emitting surface of the light-emitting apparatus by applying a thin layer of an adhesive to the second planar surface so that the adhesive fills the light-collecting groove and the central groove. 
     
     
       9. An optical correction layer as claimed in claim 8 wherein the adhesive includes a low viscosity epoxy. 
     
     
       10. An optical correction layer as claimed in claim 8 wherein the adhesive has an index of refraction equal to the indices of refraction of the plastic and the faceplate. 
     
     
       11. An optical correction layer as claimed in claim 1 wherein the continuous layer includes a matrix having a transparent inner sublayer and an optically opaque outer sublayer overlying the transparent inner sublayer; a plurality of optically transparent spherical structures embedded in the matrix to define the optically transparent regions of the optical correction layer, the spherical structures forming a monolayer of spheres so that adjacent spherical structures physically contact one another substantially at a point, the optical correction layer having a thickness equal to the diameter of the plurality of spherical structures so that substantially one point of each spherical structure is exposed at the outer surface of the optical correction layer; and   a plurality of optically transparent ellipsoidal structures embedded in the matrix to define the optical correction regions and comprising the light-redirecting means, the ellipsoidal structures forming a monolayer such that adjacent ellipsoidal structures physically contact one another at substantially a point located substantially at an endpoint of the major axis of the ellipsoidal structure, the plurality of ellipsoidal structures having a minor axis extending across the thickness of the optical correction region, the minor axis having a length equal to the diameter of the plurality of spherical structures so that substantially one point of each ellipsoidal structure is exposed at the outer surface of the optical correction layer, the exposed, substantially one point of the plurality of ellipsoidal structures being disposed opposite the gap in brightness, portions of the plurality of ellipsoidal structures being disposed opposite the light-emitting regions of the light-emitting apparatus to receive light from the light-emitting regions, wherein the light entering the plurality of ellipsoidal structures exits only at the exposed, substantially one point of the plurality of ellipsoidal structures, said exposed, substantially one point of the plurality of ellipsoidal structures being positioned opposite the gap in brightness of the light-emitting apparatus thereby concealing the gap.   
     
     
       12. An optical correction layer as claimed in claim 10 wherein the transparent inner sublayer is made of an optically transparent epoxy and the optically opaque outer sublayer is made of an epoxy having a black color. 
     
     
       13. An optical correction layer as claimed in claim 2 wherein said light-redirecting means includes a light-refracting groove formed in the second planar surface of said plastic, continuous layer, the light-refracting groove having a convex, optically transparent surface, the light-refracting groove being disposed opposite the light-emitting regions adjacent the gap so that the convex, optically transparent surface receives light from the light-emitting regions; and further including a thin layer of an adhesive being disposed between the light-emitting surface of the faceplate and the second planar surface of said plastic, continuous layer so that said plastic, continuous layer is affixed to the faceplate and so that the light-refracting groove is filled with air, the convex surface having predetermined curvature so that the refracted light is spread substantially uniformly over the first planar surface of the optical correction layer thereby concealing the gap in brightness.   
     
     
       14. An optical correction layer as claimed in claim 13 wherein the outer surface of said continuous layer includes a light-diffusing surface. 
     
     
       15. An optical correction layer as claimed in claim 13 wherein the light-refracting groove includes a circular trough. 
     
     
       16. An optical correction layer as claimed in claim 13 wherein the light-refracting groove includes a pair of elongated troughs. 
     
     
       17. An optical correction layer as claimed in claim 13 wherein the adhesive includes a high viscosity epoxy. 
     
     
       18. A field emission display comprising: a cathode structure having field emitters for emitting electrons;   a faceplate positioned to receive the emitted electrons including a first light-emitting surface and a second surface opposed to the first surface, the second surface containing a plurality of phosphor dots;   a spacer disposed between the cathode structure and the faceplate for providing structural support to prevent the collapse of the field emission display, the spacer having first and second opposed edges, the first edge positioned in abutting engagement with the cathode structure, the second edge positioned in abutting engagement with the faceplate wherein the spacer forms a gap in brightness at the light-emitting surface of the faceplate;   a plurality of light-emitting regions including a plurality of gap-adjacent phosphor dots being positioned adjacent the spacer whereby the plurality of light-emitting regions provide light which is redirected to cover the gap; and   an optical correction layer being disposed parallel to the first light-emitting surface of the faceplate and affixed to the light-emitting surface of the faceplate, the optical correction layer comprising a optical correction region having a first height and having a width equal to the sum of the width of the spacer and the widths of the plurality of light-emitting regions adjacent the spacer so that, when the optical correction region is substantially centered over the spacer, the optical correction region opposes the spacer and the plurality of light-emitting regions adjacent the spacer;   means being disposed within the optical correction region for redirecting light; and   a plurality of optically transparent regions having a second height substantially equal to the first height of the optical correction region, the optical correction region being disposed between the plurality of optically transparent regions so as to form a continuous layer of substantially uniform height, the continuous layer having first and second opposed, planar surfaces, the first planar surface including an outer surface, the second planar surface being affixed to the first light-emitting surface of the faceplate so that the optical correction region is substantially centered over the spacer,   whereby the optical correction layer provides substantially uniform brightness over the field emission display and substantially conceals the gap in brightness.   
     
     
       19. A field emission display as claimed in claim 18 wherein the spacer includes an elongated bar. 
     
     
       20. A field emission display as claimed in claim 18 wherein the spacer includes a post having opposed ends and wherein the opposed edges of the spacer include the opposed ends of the post. 
     
     
       21. A large-screen field emission display comprising: a plurality of cathode structures having field emitters for emitting electrons and having a plurality of handling edges disposed along the perimeters of the plurality of cathode structures; a backplate, the plurality of cathode structures being tiled together upon the backplate forming a tolerance gap between the plurality of cathode structures so that the tolerance gap and the plurality of handling edges form a tiling gap in the visual image of the large-screen field emission display;   a faceplate disposed opposite the plurality of cathode structures and positioned to receive the electrons emitted by the plurality of cathode structures, the faceplate including a first light-emitting surface and a second surface opposed to the first surface, the second surface containing a plurality of phosphor dots being disposed to receive electrons and emit light to form a visual image at the first light-emitting surface of the faceplate;   a spacer having first and second opposed edges for providing structural support to prevent the collapse of the large-screen field emission display, the spacer being disposed between the plurality of cathode structures and the faceplate so that the first opposed edge is in abutting engagement with the plurality of cathode structures and the second opposed edge is in abutting engagement with the faceplate;   a plurality of light-emitting regions disposed on the second surface of the faceplate adjacent the tiling gap whereby the plurality of light-emitting regions substantially provide the light which is redirected to conceal the tiling gap; and   an optical correction layer affixed to the first light-emitting surface of the faceplate, the optical correction layer comprising an optical correction region having a first height and having a width equal to the sum of the width of the tiling gap and the widths of the plurality of light-emitting regions adjacent the tiling gap so that, when the optical correction region is substantially centered over the tiling gap, the optical correction region opposes the tiling gap and the plurality of light-emitting regions adjacent the tiling gap;   means being disposed within the optical correction region for receiving and redirecting the light emitted from the light-emitting regions so as to substantially cover and conceal the tiling gap; and   a plurality of optically transparent regions having a second height substantially equal to the first height of the optical correction region, the optical correction region being disposed between the plurality of optically transparent regions so as to form a continuous layer of substantially uniform height, the continuous layer having first and second opposed, planar surfaces, the first planar surface including an outer surface, the second planar surface being affixed to the first light-emitting surface of the faceplate so that the correction region is substantially centered over the tiling gap,   whereby the optical correction layer provides substantially uniform brightness over the large-screen field emission display and substantially conceals the gap in brightness at the outer surface of the optical correction layer.   
     
     
       22. A large-screen field emission display as claimed in claim 21 wherein the plurality of light-emitting regions includes a plurality of gap-adjacent phosphor dots. 
     
     
       23. A flat fluorescent lamp suitable for use as a back light of a liquid crystal panel for use in a display device, the flat fluorescent lamp comprising: a lower glass plate coated with a fluorescent film on an inner surface thereof;   an upper glass plate coated with a fluorescent film on an inner surface thereof and having an outer, light-emitting surface, the upper glass plate disposed above the lower glass plate;   a glass side wall disposed along peripheral edges of the upper and lower glass plates and having upper and lower end faces thereof hermetically joined to the peripheral edges of the glass plates to form a hermetic discharge space between the upper and lower glass plates;   a pair of discharge electrodes arranged in parallel within the discharge space and opposed to each other;   a spacer disposed between the electrodes and for supporting the upper and lower glass plates, the spacer having a height approximately equal to the distance between the upper and lower glass plates, wherein an inner surface of the upper glass plate has an uncoated portion having no fluorescent film at a position where the spacer is in contact with the inner surface and further wherein the inner surface of the lower glass plate has an uncoated portion without any fluorescent film at a position where the spacer is in contact with the inner surface so that the spacer forms a gap in brightness at the outer, light-emitting surface of the upper glass plate;   a plurality of light-emitting regions including a plurality of segments of the fluorescent film disposed on the inner surface of the upper glass plate, the segments being adjacent the spacer whereby the plurality of light-emitting regions provide the light which is redirected to conceal the gap in brightness;   an optical correction layer being disposed parallel to the outer, light-emitting surface of the upper glass plate and further being affixed to the outer, light-emitting surface of the upper glass plate, the optical correction layer comprising an optical correction region having a first height and having a width equal to the sum of the width of the spacer and the widths of the plurality of light-emitting regions adjacent the spacer so that, when the optical correction region is substantially centered over the spacer, the optical correction region opposes the spacer and the plurality of light-emitting regions adjacent the spacer;   means being disposed within the optical correction region for receiving and redirecting light emitted from the light-emitting regions wherein the redirected light substantially conceals the gap; and   a plurality of optically transparent regions having a second height substantially equal to the first height of the optical correction region, the optical correction regions being disposed between the plurality of optically transparent regions so as to form a continuous layer of substantially uniform height, the continuous layer having first and second opposed, planar surfaces, the first planar surface including an outer surface, the second planar surface being affixed to the outer, light-emitting surface of the upper glass plate so that the optical correction region is substantially centered over the spacer,   whereby the optical correction layer provides substantially uniform brightness over the flat fluorescent lamp and substantially conceals the gap in brightness at the outer surface of the optical correction layer.   
     
     
       24. A flat fluorescent lamp as claimed in claim 23 wherein the spacer is made of ceramic. 
     
     
       25. A flat fluorescent lamp as claimed in claim 23 wherein the spacer includes an opaque coating disposed thereon so that the spacer does not transmit light. 
     
     
       26. A method for fabricating an optical correction layer for concealing a gap in brightness at a light-emitting surface of a faceplate of a light-emitting apparatus having light-emitting regions adjacent the gap, the method comprising the steps of: providing an optical correction region so that when the optical correction region is substantially centered over the gap, the optical correction region opposes the gap and the light-emitting regions adjacent the gap;   providing within the optical correction region means for redirecting light so that the light emitted by said light-emitting regions is received and redirected by the light-redirecting means to substantially cover the gap;   providing a plurality of optically transparent regions;   positioning the optical correction region between the plurality of optically transparent regions so that a continuous layer of substantially uniform height is provided having first and second opposed, planar surfaces;   whereby, upon affixing the second planar surface to the light-emitting surface of the light-emitting apparatus, the plurality of optical correction regions are substantially centered over the gaps in brightness.   
     
     
       27. A method for fabricating an optical correction layer as claimed in claim 26 wherein the steps of providing an optical correction region and providing a plurality of optically transparent regions include providing a layer of plastic; wherein the step of providing light-redirecting means within the optical correction region includes forming a light-collecting groove in the second planar surface of the layer of plastic so that the light-collecting groove has a first concave, reflective surface and a second transparent surface and so that the first concave, reflective surface and the second transparent surface meet at a vertex, the step of providing the light-redirecting means and further includes positioning the light-collecting groove so that it is disposed opposite the light-emitting regions adjacent the gap and positioning the first reflective surface to receive light from the light-emitting regions and to reflect the light to travel through the second transparent surface, the step of providing light-redirecting means further including forming a central groove in the second planar surface of said continuous layer so that the central groove has a convex, reflective surface having an apex positioned substantially opposite the center of the gap in brightness, the step of forming the central groove further includes positioning the convex, reflective surface to receive the light reflected by the light-collecting groove and providing a curvature of the convex surface so that the light is reflected and redirected to substantially cover and conceal the gap in brightness.   
     
     
       28. A method for fabricating an optical correction layer as claimed in claim 27 wherein the step of providing light-redirecting means further includes applying a thin layer of an adhesive to the second planar surface so that the adhesive completely fills the light-collecting groove and the central groove whereby the optical correction layer is affixed to the light-emitting surface of the light-emitting apparatus by positioning the thin layer of adhesive in abutting engagement with the light-emitting surface of the light-emitting apparatus.   
     
     
       29. A method for fabricating an optical correction layer as claimed in claim 28 wherein the step of applying a thin layer of an adhesive includes applying a thin layer of a low viscosity epoxy. 
     
     
       30. A method for fabricating an optical correction layer as claimed in claim 27 wherein the steps of forming a light-collecting groove and forming a central groove include: providing a hard surface;   forming the complement of the desired groove pattern on the hard surface;   pressing the plastic layer onto the hard surface under predetermined conditions of temperature and pressure, thereby embossing the desired groove pattern into the plastic layer; and   applying a reflective coating onto the concave surface of the light-collecting groove and onto the convex surface of the central groove.   
     
     
       31. A method for fabricating an optical correction layer as claimed in claim 30 wherein the step of applying a reflective coating includes applying an aluminum coating onto the concave surface of the light-collecting groove and onto the convex surface of the central groove. 
     
     
       32. A method for fabricating an optical correction layer as claimed in claim 26 wherein the steps of providing a plurality of optical correction regions and providing a plurality of optically transparent regions include providing a layer of plastic; and wherein the step of providing light-redirecting means within the optical correction region includes forming a light-refracting groove in the second planar surface of the layer of plastic so that the light-refracting groove has a convex, optically transparent surface having a predetermined curvature, the step of forming a light-refracting groove further includes positioning the light-refracting groove opposite the light-emitting regions adjacent the gap so that the convex, optically transparent surface receives light from the light-emitting regions, the step of providing light-redirecting means further including applying a thin layer of an adhesive to the light-emitting surface of the faceplate and then placing the optical correction layer in physical contact with the adhesive so that the adhesive contacts the flat surfaces of the second planar surface of the layer of plastic and so that the light-refracting groove is filled with air, the step of forming a light-refracting groove further includes providing a curvature of the convex surface so that the light refracted at the convex surface spreads substantially uniformly over the first planar surface of the optical correction layer thereby concealing the gaps in brightness.   
     
     
       33. A method for fabricating an optical correction layer as claimed in claim 32 wherein the step of applying a thin layer of an adhesive includes applying a thin layer of a high viscosity epoxy. 
     
     
       34. A method for fabricating an optical correction layer as claimed in claims 32 wherein the step of forming a light-refracting groove includes providing a hard surface; forming the complement of the desired groove pattern on the hard surface; and   pressing the plastic layer onto the hard surface under predetermined conditions of temperature and pressure, thereby embossing the desired groove pattern into the plastic layer.